Optical fiber connectors can be used to connect optical fibers in a variety of applications including: telecommunications networks, local area networks, data center links, and internal links in high performance computers. These connectors can be grouped into single fiber and multiple fiber designs and also grouped by the type of contact. Common contact methods include: physical contact wherein the mating fiber tips are polished to a smooth finish and pressed together; index matched, wherein a compliant material with an index of refraction that is matched to the core of the fiber fills a small gap between the mated fibers' tips; and air gap connectors, wherein the light passes through a small air gap between the two fiber tips. With each of these contact methods a small bit of dust at the tips of the mated fibers can greatly increase the light loss.
Another type of optical connector is referred to as an expanded beam connector. Expanded beam connectors can be either collimating, or conjugate focus designs, both of which give a large beam diameter at the surface of the output optical element, where dirt can collect. This type of connector allows the light beam in the source connector to exit the fiber core and diverge within the connector for a short distance before the light leaves the connector with a diameter substantially greater than the core. In the receiving connector the beam is then focused back to its original diameter on the tip of the receiving fiber. This type of connector is less sensitive to dust and other forms of contamination.
Backplane optical connectors will become essential components of high-performance computers, data centers, and telecom switching systems in the near future, as line rates of data transmission migrate from the current 10 Gb/sec/line to 25 Gb/sec/line in the next few years. It would be advantageous to provide expanded beam connectors enabling optical interconnect systems which are lower cost and higher performance alternatives to copper connections that are currently being used in the 10 Gb/sec interconnects.